// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// Platform-specific code for Linux goes here. For the POSIX-compatible
// parts, the implementation is in platform-posix.cc.

#include <pthread.h>
#include <semaphore.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/syscall.h>
#include <sys/time.h>

// Ubuntu Dapper requires memory pages to be marked as
// executable. Otherwise, OS raises an exception when executing code
// in that page.
#include <errno.h>
#include <fcntl.h> // open
#include <stdarg.h>
#include <strings.h> // index
#include <sys/mman.h> // mmap & munmap
#include <sys/stat.h> // open
#include <sys/types.h> // mmap & munmap
#include <unistd.h> // sysconf

#include <cmath>

#undef MAP_TYPE

#include "src/base/macros.h"
#include "src/base/platform/platform-posix-time.h"
#include "src/base/platform/platform-posix.h"
#include "src/base/platform/platform.h"

namespace v8 {
namespace base {

#ifdef __arm__

    bool OS::ArmUsingHardFloat()
    {
        // GCC versions 4.6 and above define __ARM_PCS or __ARM_PCS_VFP to specify
        // the Floating Point ABI used (PCS stands for Procedure Call Standard).
        // We use these as well as a couple of other defines to statically determine
        // what FP ABI used.
        // GCC versions 4.4 and below don't support hard-fp.
        // GCC versions 4.5 may support hard-fp without defining __ARM_PCS or
        // __ARM_PCS_VFP.

#define GCC_VERSION \
    (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
#if GCC_VERSION >= 40600 && !defined(__clang__)
#if defined(__ARM_PCS_VFP)
        return true;
#else
        return false;
#endif

#elif GCC_VERSION < 40500 && !defined(__clang__)
        return false;

#else
#if defined(__ARM_PCS_VFP)
        return true;
#elif defined(__ARM_PCS) || defined(__SOFTFP__) || defined(__SOFTFP) || !defined(__VFP_FP__)
        return false;
#else
#error \
    "Your version of compiler does not report the FP ABI compiled for."     \
       "Please report it on this issue"                                        \
       "http://code.google.com/p/v8/issues/detail?id=2140"

#endif
#endif
#undef GCC_VERSION
    }

#endif // def __arm__

    TimezoneCache* OS::CreateTimezoneCache()
    {
        return new PosixDefaultTimezoneCache();
    }

    std::vector<OS::SharedLibraryAddress> OS::GetSharedLibraryAddresses()
    {
        std::vector<SharedLibraryAddress> result;
        // This function assumes that the layout of the file is as follows:
        // hex_start_addr-hex_end_addr rwxp <unused data> [binary_file_name]
        // If we encounter an unexpected situation we abort scanning further entries.
        FILE* fp = fopen("/proc/self/maps", "r");
        if (fp == nullptr)
            return result;

        // Allocate enough room to be able to store a full file name.
        const int kLibNameLen = FILENAME_MAX + 1;
        char* lib_name = reinterpret_cast<char*>(malloc(kLibNameLen));

        // This loop will terminate once the scanning hits an EOF.
        while (true) {
            uintptr_t start, end, offset;
            char attr_r, attr_w, attr_x, attr_p;
            // Parse the addresses and permission bits at the beginning of the line.
            if (fscanf(fp, "%" V8PRIxPTR "-%" V8PRIxPTR, &start, &end) != 2)
                break;
            if (fscanf(fp, " %c%c%c%c", &attr_r, &attr_w, &attr_x, &attr_p) != 4)
                break;
            if (fscanf(fp, "%" V8PRIxPTR, &offset) != 1)
                break;

            // Adjust {start} based on {offset}.
            start -= offset;

            int c;
            if (attr_r == 'r' && attr_w != 'w' && attr_x == 'x') {
                // Found a read-only executable entry. Skip characters until we reach
                // the beginning of the filename or the end of the line.
                do {
                    c = getc(fp);
                } while ((c != EOF) && (c != '\n') && (c != '/') && (c != '['));
                if (c == EOF)
                    break; // EOF: Was unexpected, just exit.

                // Process the filename if found.
                if ((c == '/') || (c == '[')) {
                    // Push the '/' or '[' back into the stream to be read below.
                    ungetc(c, fp);

                    // Read to the end of the line. Exit if the read fails.
                    if (fgets(lib_name, kLibNameLen, fp) == nullptr)
                        break;

                    // Drop the newline character read by fgets. We do not need to check
                    // for a zero-length string because we know that we at least read the
                    // '/' or '[' character.
                    lib_name[strlen(lib_name) - 1] = '\0';
                } else {
                    // No library name found, just record the raw address range.
                    snprintf(lib_name, kLibNameLen, "%08" V8PRIxPTR "-%08" V8PRIxPTR, start,
                        end);
                }
                result.push_back(SharedLibraryAddress(lib_name, start, end));
            } else {
                // Entry not describing executable data. Skip to end of line to set up
                // reading the next entry.
                do {
                    c = getc(fp);
                } while ((c != EOF) && (c != '\n'));
                if (c == EOF)
                    break;
            }
        }
        free(lib_name);
        fclose(fp);
        return result;
    }

    void OS::SignalCodeMovingGC()
    {
        // Support for ll_prof.py.
        //
        // The Linux profiler built into the kernel logs all mmap's with
        // PROT_EXEC so that analysis tools can properly attribute ticks. We
        // do a mmap with a name known by ll_prof.py and immediately munmap
        // it. This injects a GC marker into the stream of events generated
        // by the kernel and allows us to synchronize V8 code log and the
        // kernel log.
        long size = sysconf(_SC_PAGESIZE); // NOLINT(runtime/int)
        FILE* f = fopen(OS::GetGCFakeMMapFile(), "w+");
        if (f == nullptr) {
            OS::PrintError("Failed to open %s\n", OS::GetGCFakeMMapFile());
            OS::Abort();
        }
        void* addr = mmap(OS::GetRandomMmapAddr(), size, PROT_READ | PROT_EXEC,
            MAP_PRIVATE, fileno(f), 0);
        DCHECK_NE(MAP_FAILED, addr);
        CHECK(Free(addr, size));
        fclose(f);
    }

    void OS::AdjustSchedulingParams() { }

} // namespace base
} // namespace v8
